911 (number)
911 (nine hundred [and] eleven) is the integer following 910 and preceding 912.
| 911 | |
|---|---|
| Cardinal | Nine hundred and eleven |
| Ordinal | 911th |
| Factorization | Prime |
| Roman numeral | CMXI |
| Binary | 1110001111 |
| Hexadecimal | 38F |
It is a prime number, a Sophie Germain prime and the sum of three consecutive primes (293 + 307 + 311). It is an Eisenstein prime with no imaginary part and real part of the form 3n − 1. Since 913 is a semiprime, 911 is a Chen prime. It is also a centered decagonal number.
There are 911 inverse semigroups of order 7 (sequence A001428 in OEIS)
911 is obtained by concatenating its sum of digits and product of digits.
9-1-1 is the emergency telephone number for the North American Numbering Plan (NANP).
As "911" or "9/11", typically pronounced "nine-eleven", it is commonly used to refer the calendar dates November 9 or September 11, depending on which date notation is used. The latter usage most commonly refers to the September 11, 2001 attacks in the United States.
The Madrid Attack came exactly 911 days after 9/11.
[edit] See also
- 911 C.E., the year
- 9-1-1, the telephone number of most local emergency agencies in the United States and Canada.
